add option to stop time

launch

@@ -1,12 +1,13 @@
 #!/usr/bin/env bash
 
 executable="$1"
+options="$2"
 prime="prime-run"
 
 if command -v $prime &> /dev/null
 then
-    echo "launching $executable with nvidia prime offloading"
+    echo "launching $executable $options with nvidia prime offloading"
-    $prime $executable
+    $prime $executable $options
 else
-    $executable
+    $executable $options
 fi

makefile

@@ -46,7 +46,11 @@ clean:
 	-rm -r $(BIN_DIR)
 	-rm */*.o
 
+# TODO: extract run-* out to like, python scripts? arguments can be implemented with argparse to
+# manage simple interface with C binary
 run: $(TARGET)
-	$(LAUNCH) $(TARGET)
+	$(LAUNCH) $(TARGET) 1.0
+run-converge: $(TARGET) 
+	$(LAUNCH) $(TARGET) 0.0
 
 .PHONY: run clean

src/cam.c

@@ -2,10 +2,8 @@
 
 const float FOVY = 90.0;
 
-void updateCameraUniforms(GLuint shaderProgram, float aspect)
+void updateCameraUniforms(GLuint shaderProgram, float aspect, float t)
 {
-    float t = now();
-
     // wobble up dir
     vec3 cdir, cright, cup;
     vec3 up = {0.1*sin(t),1.0,0.05*cos(0.5*t)};

src/cam.h

@@ -6,4 +6,4 @@
 
 #include "clock.h"
 
-void updateCameraUniforms(GLuint shaderProgram, float aspect);
+void updateCameraUniforms(GLuint shaderProgram, float aspect, float t);

src/clock.c

@@ -1,6 +1,6 @@
 #include "clock.h"
 
-float now() 
+float now(struct Epoch t) 
 { 
-    return (float)SDL_GetTicks() / 1000.0; 
+    return t.speed * (float)SDL_GetTicks() / 1000.0;
 }

src/clock.h

@@ -2,5 +2,10 @@
 
 #include <SDL2/SDL.h>
 
+struct Epoch
+{
+    float speed;
+};
+
 // seconds since program start
-float now();
+float now(struct Epoch e);

src/gfx.c

@@ -174,16 +174,6 @@ void setVertexAttributes()
     // color
     glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, stride, (void*)(3*sizeof(float)));
     glEnableVertexAttribArray(1);
-
-
-
-
-
-
-
-
-
-
     // uv 
     glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, stride, (void*)(6*sizeof(float)));
     glEnableVertexAttribArray(2);

src/main.c

@@ -10,12 +10,13 @@
 const int WIDTH = 420;
 const int HEIGHT = 420;
 
-void updateUniforms(GLuint shaderProgram);
+void updateUniforms(GLuint shaderProgram, float t);
 
 SDL_Window *window;
 
 struct Shaders shaders;
 struct Textures textures;
+struct Epoch epoch;
 
 void initialise()
 {
@@ -32,15 +33,29 @@ void initialise()
     createTextures(WIDTH, HEIGHT, shaders, &textures);
 }
 
-int main()
+void parseArgs(int argc, char* argv[], struct Epoch* e)
 {
+    // check we have the right number of arguments
+    if (argc != 2)
+    {
+        fprintf(stderr, "usage: oglc TIMESPEED\n");
+    }
+
+    sscanf(argv[1], "%f", &(e->speed));
+}
+
+int main(int argc, char* argv[])
+{
+    parseArgs(argc, argv, &epoch);
+
     initialise();
 
-    float start = now();
+    float start = now(epoch);
     int frames;
     for (frames = 0; !checkQuit(); frames++)
     {
         GLuint shader;
+        float t = now(epoch);
 
         // prepass
         // TODO: write output to different texture than main output
@@ -48,18 +63,17 @@ int main()
         glActiveTexture(GL_TEXTURE0);
         glBindTexture(GL_TEXTURE_2D, textures.g0);
         glUseProgram(shader);
-        updateUniforms(shader);
+        updateUniforms(shader, t);
         glDispatchCompute((GLuint)WIDTH, (GLuint)HEIGHT, 1);
 
         // make sure we're finished writing to the texture before trying to read it
         glMemoryBarrier(GL_ALL_BARRIER_BITS);
 
-        // dispatch compute shaders
         shader = shaders.lighting;
         glActiveTexture(GL_TEXTURE0);
         glBindTexture(GL_TEXTURE_2D, textures.target);
         glUseProgram(shader);
-        updateUniforms(shader);
+        updateUniforms(shader, t);
         //int loc = glGetUniformLocation(shader, "_g0");
         //glUniform1i(loc, textures.g0);
         glDispatchCompute((GLuint)WIDTH, (GLuint)HEIGHT, 1);
@@ -67,6 +81,18 @@ int main()
         // make sure we're finished writing to the texture before trying to read it
         glMemoryBarrier(GL_SHADER_IMAGE_ACCESS_BARRIER_BIT);
 
+        // TODO: frame blending
+        //
+        // before we get to our normal rendering pass we need to blend our samples
+        // across multiple frames. to do this, we should maintain an accumulation
+        // buffer where we can store pixel data while a new frame is being generated.
+        // this can be a collection of two buffers, where one is written to and the 
+        // other is read from. to render a new frame, the newly sampled raw frame can
+        // be combined with data from the previous frame. by repeatedly taking the
+        // average over a large number of frames a cleaner image can be generated.
+        // this is most effective for static images, and will produce motion blur on
+        // a moving image.
+
         // normal drawing pass
         shader = shaders.quad;
         glUseProgram(shader);
@@ -78,7 +104,7 @@ int main()
         SDL_GL_SwapWindow(window);
     }
 
-    float elapsed = now()-start;
+    float elapsed = now(epoch)-start;
     printf("%d frames in %fs [%f fps]\n", 
             frames, 
             elapsed, 
@@ -87,7 +113,7 @@ int main()
     return 0;
 }
 
-void updateUniforms(GLuint shaderProgram)
+void updateUniforms(GLuint shaderProgram, float t)
 {
     // update random values
     vec4 seed = 
@@ -100,19 +126,17 @@ void updateUniforms(GLuint shaderProgram)
     int loc = glGetUniformLocation(shaderProgram, "_seed");
     glUniform4fv(loc, 1, seed);
 
-    // update time
-    float t = now();
     float sin_t = sin(t);
     loc = glGetUniformLocation(shaderProgram, "_t");
     glUniform4f(loc, t, sin_t, (1.0 + sin_t)*0.5, 0.0f);
 
     // update camera
     float aspect = (float)WIDTH/(float)HEIGHT;
-    updateCameraUniforms(shaderProgram, aspect);
+    updateCameraUniforms(shaderProgram, aspect, t);
 
     // make and update spheres
     const int sphereCount = 42;
     struct Sphere spheres[sphereCount];
-    makeSpheres(spheres, sphereCount);
+    makeSpheres(spheres, sphereCount, t);
     updateSphereUniforms(shaderProgram, spheres, sphereCount);
 }

src/sphere.c

@@ -1,9 +1,7 @@
 #include "sphere.h"
 
-void makeSpheres(struct Sphere *spheres, int count)
+void makeSpheres(struct Sphere *spheres, int count, float t)
 {
-    //float t = time();
-
     vec3 albedos[] = 
     {
         {0.0,0.0,1.0},
@@ -21,7 +19,6 @@ void makeSpheres(struct Sphere *spheres, int count)
     float x;
     vec3 sc = {0.0,0.0,1.0};
 
-    float t = now();
     for (int i = 0; i < count; i++)
     {
         x = 2.0*CGLM_PI * (float)i/(float)count;

src/sphere.h

@@ -16,7 +16,7 @@ struct Sphere
     int material;
 };
 
-void makeSpheres(struct Sphere *spheres, int count);
+void makeSpheres(struct Sphere *spheres, int count, float t);
 struct Sphere makeSphere(vec3 center, float radius, vec3 albedo, int material);
 //void updateSphereUniform(GLuint shaderProgram, struct Sphere sphere);
 void updateSphereUniforms(GLuint shaderProgram, struct Sphere *spheres, int count);